The invention relates generally to an electrophysiological (xe2x80x9cEPxe2x80x9d) catheter system for use on biological tissue within a biological site, and more particularly, to a combined mapping and ablating catheter system for use in and around the pulmonary veins.
The heart beat in a healthy human is controlled by the sinoatrial node (xe2x80x9cS-A nodexe2x80x9d) located in the wall of the right atrium. The S-A node generates electrical signal potentials that are transmitted through pathways of conductive heart tissue in the atrium to the atrioventricular node (xe2x80x9cA-V nodexe2x80x9d) which in turn transmits the electrical signals throughout the ventricle by means of the His and Purkinje conductive tissues. Improper growth of, or damage to, the conductive tissue in the heart can interfere with the passage of regular electrical signals from the S-A and A-V nodes. Electrical signal irregularities resulting from such interference can disturb the normal rhythm of the heart and cause an abnormal rhythmic condition referred to as xe2x80x9ccardiac arrhythmia.xe2x80x9d
Cardiac arrhythmia, including atrial arrhythmia, may be of a multiwavelet reentrant type, characterized by multiple asynchronous loops of electrical impulses that are scattered about the atrial chamber and are often self propagating. In the alternative or in addition to the multiwavelet reentrant type, cardiac arrhythmia may also have a focal origin, such as when an isolated region of tissue in an atrium fires autonomously in a rapid, repetitive fashion.
While there are different treatments for cardiac arrhythmia, including the application of anti-arrhythmia drugs, in many cases ablation of the damaged tissue can restore the correct operation of the heart. Such ablation can be performed by percutaneous ablation, a procedure in which a catheter is percutaneously introduced into the patient and directed through an artery or vein to the atrium or ventricle of the heart to perform single or multiple diagnostic, therapeutic, and/or surgical procedures. In such case, an ablation procedure is used to destroy the tissue causing the arrhythmia in an attempt to remove the electrical signal irregularities or create a conductive tissue block to restore normal heart beat or at least an improved heart beat. Successful ablation of the conductive tissue at the arrhythmia initiation site usually terminates the arrhythmia or at least moderates the heart rhythm to acceptable levels. A widely accepted treatment for arrhythmia involves the application of RF energy to the conductive tissue.
In the case of atrial fibrillation (xe2x80x9cAFxe2x80x9d), a procedure published by Cox et al. and known as the xe2x80x9cMaze procedurexe2x80x9d involves the formation of continuous atrial incisions to prevent atrial reentry and to allow sinus impulses to activate the entire myocardium. While this procedure has been found to be successful, it involves an intensely invasive approach. It is more desirable to accomplish the same result as the Maze procedure by use of a less invasive approach, such as through the use of an appropriate EP catheter system providing RF ablation therapy. In this therapy, transmural ablation lesions are formed in the atria to prevent atrial reentry and to allow sinus impulses to activate the entire myocardium.
One such EP catheter system, as disclosed in U.S. Pat. Nos. 6,059,778 and 6,096,036, includes a plurality of spaced apart band electrodes located at the distal-end of the catheter and arranged in a linear array. The band electrodes are positioned proximal heart tissue. RF energy is applied through the electrodes to the heart tissue to produce a series of long linear lesions similar to those produced by the Maze procedure.
As previously mentioned, cardiac arrhythmia, such as atrial fibrillation, may be focal in nature. The foci, defined by regions exhibiting a consistent and centifugal pattern of electrical activation, may act as either a trigger of atrial fibrillation paroxysmal or may even sustain fibrillation. Such focal arrhythmia are known to originate from a tissue region along the pulmonary veins of the left atrium, and more particularly in the superior pulmonary veins.
Procedures for the treatment of focal arrhythmia involving the pulmonary vein generally require the use of two separate catheter systemsxe2x80x94a mapping catheter system for locating the foci and an ablation catheter system for ablating the foci. Both catheter systems include their respective mapping or ablation catheter and either a guiding catheter or a guide wire for introducing the catheter into the left atrium of the heart. During a typical procedure, the mapping catheter is first introduced into the left atrium through a puncture in the septum between the right and left atria. The mapping catheter is then guided into the pulmonary vein. While the mapping catheter is still within the heart, the ablation catheter is introduced into the left atrium through either the same puncture as the mapping catheter or a separate puncture. Using the mapping catheter, the foci of the arrhythmia is located using any of several well known mapping techniques. After it is determined that the foci are located within the pulmonary vein, the ablation catheter is positioned either in the pulmonary vein or around the pulmonary vein ostium and the tissue is ablated. The procedure thus described requires the simultaneous placement of two separate catheters into the left atrium through either one or two separate introduction paths. In the case of the left atrium such introduction paths comprise punctures through the atrial septum between the right and left atria. Passing two catheters through a single puncture or two separate punctures increases patient trauma. It also increases the likelihood of damaging the heart through tearing of the septum.
Hence, those skilled in the art have recognized a need for a catheter system having two independent catheters, each capable of being introduced into the heart via a single transseptal introduction path. The need for a combined mapping and ablation catheter system for use in the pulmonary vein has also been recognized. The invention fulfills these needs and others.
Briefly, and in general terms, the invention is directed to a combination mapping and ablating catheter system for use during electrophysiological procedures in and around various biological sites, including the pulmonary veins.
In a first aspect, the invention relates to a catheter system that includes an outer catheter having a lumen therethrough and a distal-end region carrying a first electrode system. The catheter system also includes an inner catheter that is sized to fit within and slide through the lumen of the outer catheter. The inner catheter has a distal-end region carrying a second electrode system.
By providing an outer catheter having a lumen through which a separate inner catheter may slide, the invention allows for the simultaneous placement of two separate catheters into a biological site through a signal introduction path. As such, the likelihood of damaging the biological site is substantially reduced.
In detailed aspects of the invention, either one or both of the outer catheter and inner catheter further include a tendon having a distal end attached to the distal-end region of the respective catheter and a proximal end exiting the proximal end of the catheter. The tendon is attached such that movement of the tendon along the length of the catheter causes the distal-end region of that catheter to curve. In a another detailed aspect, the outer catheter further comprises a shaped-memory stylet for imparting a preshaped curve to the distal-end region of the outer catheter. In a further detailed aspect, the preshaped curve has a radius of curvature and the catheter further comprises a tendon having a distal end attached to the distal end of the catheter and a proximal end exiting the proximal end of the catheter. The tendon is attached such that movement of the tendon along the length of the catheter decreases the radius of curvature.
In another detailed facet of the invention, the outer catheter includes an outer tubular member and an inner tubular member slidably disposed within the outer tubular member. The inner tubular member defines the lumen of the outer catheter. The other catheter also includes a plurality of outwardly bendable segments. The segments are secured at their distal ends to the distal-end region of the inner tubular member and at their proximal ends to the outer tubular member at a point proximal the attachment points of the distal ends. Movement of the inner tubular member in the proximal direction relative the outer tubular member causes the segments to bend outward.
In another aspect, the invention relates to a catheter system that includes an outer catheter having tubular wall defining a lumen. The tubular wall includes a sidewall orifice. The outer catheter also includes a distal-end region carrying a first electrode system and a proximal-end region. The catheter system further includes an inner catheter sized to fit within the lumen of the outer catheter and to slide therein. The inner catheter is also sized to fit through the sidewall orifice. The inner catheter has a distal-end region carrying a second electrode system.
In a detailed facet of the invention, the tubular member comprises a resiliently deformable junction section between the distal-end region and the proximal end region. The junction section has a normally bent form that generally aligns the center of the sidewall orifice with the axis of the proximal-end region of the tubular wall. In another detailed aspect, the outer catheter further includes a tendon having a distal end attached proximate the inner wall of the tubular member and a proximal end exiting the proximal end of the tubular member. Movement of the tendon along the length of the tubular member causes the distal-end region to deflect about the junction section relative to the proximal-end region. In yet another detailed aspect, the outer catheter includes a shaped-memory stylet for imparting a generally circular curve to the distal-end region of the tubular wall. The curve lies substantially within a first plane. The inner catheter also includes a shaped-memory stylet for imparting a generally circular curve to the distal-end region of the inner catheter. This curve lies substantially within a second plane that is substantially parallel to the first plane.
In another detailed facet of the invention the first electrode system and the second electrode system each comprise a plurality of band electrodes positioned along the length of the their respective distal-end region. The catheter system further comprises an alignment system that is adapted to align the curved distal-end region of the inner catheter with the curved distal-end region of the outer catheter such that the band electrodes of the respective catheters are aligned with each other. In a further detailed aspect, the alignment system comprises a pair of markers, each visible under fluoroscopy. One marker is carried on the proximal region of the inner catheter while the other marker is carried on the proximal region of the outer catheter.
In another further detailed aspect, the alignment system comprises a groove along the outer surface of the proximal region of the inner catheter and a complementary protrusion along the inner surface of the outer catheter.
In another facet, the invention relates to a method of performing an electrophysiological procedure on biological tissue within a biological site. The method includes positioning a first catheter, having a distal-end region carrying a first electrode system, within the biological site proximate the biological tissue. The method further includes sensing electrical activity within the tissue through the first electrode system and processing the electrical activity to identify the origin of an electrophysiological condition. The method further includes guiding a second catheter, having a distal-end region carrying a second electrode system, via the first catheter, into the biological site. The method also includes positioning the second catheter such that the second electrode system is adjacent the identified origin and applying energy to the second electrode system to ablate the identified origin.
In a detailed aspect of the invention, the first catheter includes a tubular wall defining a lumen and guiding the second catheter includes sliding the second catheter through the lumen. In a further detailed facet, positioning the second catheter such that the second electrode system is adjacent the identified source includes sliding the second catheter through the lumen until the second electrode system is substantially coincident with the first electrode system and repositioning the first catheter relative the second catheter to expose the second electrode system. In another detailed aspect, the second catheter includes a tubular wall defining a lumen and guiding the second catheter includes sliding the second catheter over the first catheter. In a further detailed aspect, positioning the second catheter such that the second electrode system is adjacent the identified source includes sliding the second catheter over the first catheter until the second electrode system is coincident with the first electrode system.
In another facet, the invention relates to a method of performing an electrophysiological procedure on biological tissue proximate a pulmonary vein. The method includes positioning a first catheter, having a distal-end region carrying a first electrode system, near the ostium of the pulmonary vein and guiding a second catheter, via the first catheter, into the pulmonary vein. The second catheter has a distal-end region carrying a second electrode system. The method further includes sensing electrical activity within the pulmonary-vein tissue through the first electrode system, processing the electrical activity to confirm the existence of an abnormal electrophysiological condition originating within the pulmonary vein and upon confirmation, applying energy to the first electrode system to ablate the tissue near the ostium.
In a detailed facet of the invention, the first catheter further includes a resiliently deformable shaped-memory stylet for imparting a generally circular curve to the distal-end region of the first catheter and positioning the first catheter near the ostium of the pulmonary vein includes the steps of straightening the distal-end region to allow entry of the distal-end region into the heart, allowing the distal-end region to assume its curved shape and positioning the distal-end region at the ostium such that the curved portion of the region contacts the tissue defining the ostium. In another detailed aspect, the second catheter further includes a resiliently deformable shaped-memory stylet for imparting a generally circular curve to the distal-end region of the second catheter and positioning the second catheter within the pulmonary vein includes the steps of straightening the distal-end region to allow entry of the distal-end region into the pulmonary vein, allowing the distal-end region to assume its curved shape and positioning the distal-end region within the vein such that the curved portion of the region contacts the tissue defining the vein lumen.
In another aspect, the invention relates to a catheter system including a catheter sheath carrying a circumferentially expandable member at its distal end. The catheter system further includes a first electrode system positioned on the expandable member and a second electrode system positioned on the expandable member, proximal the first electrode system.
In a detailed aspect of the invention, the expandable member includes a distal segment with a first expandable diameter and a proximal segment with a second expandable diameter greater than the first expandable diameter. The first electrode system is positioned at the distal segment and the second electrode system positioned at the proximal segment. In further detailed aspects either one or both of the first electrode system and second electrode system includes a plurality of electrode elements arranged to form a circumferential band around the expandable member.
In another aspect, the invention relates to a method of performing an electrophysiological procedure on biological tissue proximate a pulmonary vein. The method includes positioning a circumferentially expandable member having a distal-end region with a first electrode system and a proximal-end region with a second electrode system in the heart such that the distal-end region is at least partially within the pulmonary vein and the proximal-end region is adjacent the tissue defining the ostium of the pulmonary vein. The method also includes expanding the circumferentially expandable member such that the first electrode system contacts the tissue defining the pulmonary vein and the second electrode system contacts the tissue defining the ostium, sensing electrical activity within the pulmonary-vein tissue through the first electrode system and processing the electrical activity to confirm the existence of an abnormal electrophysiological condition originating within the pulmonary vein. The method further includes applying energy to the first electrode system to ablate the tissue near the ostium upon confirmation of the existence of an abnormal electrophysiological condition.
These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings which illustrate by way of example the features of the invention.